1. Technical Field
The present invention is directed toward double-hung windows, and more particularly to tilt latches for double-hung windows.
2. Background Art
Double-hung windows include two window sashes typically mounted for vertical movement along adjacent parallel tracks. Traditional double-hung window designs provide poor washability, however, since it is difficult for a person located inside the room to wash the outside of the window pane. To fully wash the outer surface of such windows (which outer surface is the one which is most often in need of cleaning), the person cleaning the window must typically go outside the dwelling. This is not only extremely inconvenient (as the person has to walk significant distances merely to wash both sides of a single window), it can also force a window washer, when trying to wash double-hung windows located at significant heights, to face the undesirable choice of either risking injury by climbing to that height or doing a relatively poor job of washing by merely reaching from a distance with a hose or a special long pole apparatus of some type. Such cleaning is still further complicated where there are screens or storm windows which must be removed prior to washing.
To overcome this problem, tilting latches for double-hung windows have sometimes been provided. Such latches have generally been installed in opposite ends of a top horizontal rail of the upper and lower sash, and typically include a tongue which during normal operation extends out from the side of the sash into the sash track in the window frame to guide the sash for typical vertical movement. The tongue of each latch is retracted in some manner when washing is desired to free the top rail of the sash from the track so that the sash may be suitably pivoted inwardly about pivots guiding the bottom rail of the sash in the track and thereby allow the washer to easily reach the outside surface of the window pane of that sash.
The tongue in many of the prior art latches is commonly biased outwardly into the track by a spring structure or the like, with the tongue retracted inwardly by the washer manually pulling the tongues in toward the center of the top rail against the force of the spring (see, for example, U.S. Pat. No. 5,139,291). However, with such structures, the tongues can be difficult to move, not only due to the spring but also due to binding which can almost inevitably arise over the long period of use of the latches (due to grime which can gum up the latch as well as bending of the tongue which can occur from the stresses arising during normal sliding operation of the tongue in the track). Such problems can cause the person trying to retract the tongues to hurt their hands and, if the tongue is too difficult to move, they may just give up on trying to wash the window entirely and thereby lose the advantage of the latch structure completely.
Further, such tilt latches have typically had an assortment of complex structures which are difficult and time consuming (and therefore costly) to assemble. Still further, such tilt latches have commonly been made of plastic (in part due to cost constraints), with the result being that excessive load applied to the lever arm when unlocking the tilt latch can too easily damage the structure. Also, such latches may not adequately indicate whether they have been properly returned to their extended position after washing, with the possible result being that the window sash could unexpectedly pivot inwardly at some point thereafter, likely breaking with window pane as well as perhaps injuring any person nearby at the time.
Some attempts have also been made to control movement of the tongue by a pivoting lever. While this can aid in retracting the tongue, such latches have nevertheless encountered many of the above described problems (e.g., difficult, time consuming and costly to assemble, inadequately resistant to damage, and susceptible to allowing the window sash to inadvertently be inadequately secured to the track), and have further resulted in other problems. For example, some of these type latches are susceptible to damage in certain conditions of use. Further, latches of this type can have difficulty providing smooth and consistent operation over their long expect life.
The present invention is directed toward overcoming one or more of the problems set forth above.